1. Technical Field
The present invention relates to a method of temporarily adhering a stack of sheets together to facilitate drilling a hole through the stack of sheets.
2. Related Art
A stack of sheets may be adhered together around a periphery of each sheet using an adhesive such as a glass cloth impregnated with epoxy. Hole burring occurs as a drill passes through the stack. Additionally, each sheet separates from an adjacent sheet as the drill passes between the sheets. This results in the whole stack of sheets expanding. An alternate method includes the permanent application of cured epoxy over the entire surface of each sheet in the stack. The thickness of the epoxy between each sheet results in excessive thickness of the overall stack as well as composites which will contain the separated sheets when they are processed into composites. A method of drilling a stack of sheets that overcomes these problems plus others is desired.
A first general aspect of the present invention provides a structure comprising:
a stack comprising a plurality of sheets such that each successive sheet is coupled with a removable adhesive between each sheet; and
an opening extending through the plurality of sheets within the stack.
A second general aspect of the present invention provides a structure comprising:
a plurality of stacks wherein each successive stack is coupled with a removable adhesive to an intermediate layer between each stack wherein each intermediate layer prevents burr formation; and
wherein each stack comprises a plurality of sheets such that each successive sheet is coupled with a removable adhesive between each sheet.
A third general aspect of the present invention provides a method comprising:
forming a stack by stacking a plurality of sheets;
applying an adhesive between each successive sheet;
applying a vacuum to the plurality of sheets;
heating the plurality of sheets to melt the solid adhesive;
applying a first pressure to the sheets;
cooling the plurality of sheets; and
forming an opening through the plurality of sheets; and
separating the sheets.
A forth general aspect of the present invention provides a method comprising:
forming a stack by stacking a plurality of sheets;
applying a thin layer of water between each successive sheet;
applying a pressure to the sheets; and
forming an opening through the plurality of sheets.